Stirling Thermal Motors, Inc., (STM) has been developing a general purpose Heat Pipe Gas Combustion System (HPGC) suitable for use with the STM4-120 Stirling Engine. The HPGC consists of a parallel plate recuperative preheater, a finned heat pipe evaporator and a film-cooled gas combustor. The principal component of the HPGC is the heat pipe evaporator which collects liquid sodium and distributes it evenly over the heat transfer surfaces. The liquid sodium evaporates and flows to the condensers where it delivers its latent heat.
This paper presents the design and test results of different size HPGC units. Measurements with calorimeters yielded system efficiencies of 85 to 90% at different heat transport capacities ranging from 10 to 95 kW thermal. Improvements in the HPGC design resulting from different scale system testing are presented.